Most vehicular tires have a rubber tread of a lug and groove configuration. Many tires are of a co-extruded cap/base construction, wherein the tread cap is an outer rubber layer which contains the lug and groove configuration.
The outer lug surfaces of the tread are normally intended to constitute the running surface of the tire and to promote ground-contacting traction for the tread.
It is appreciated that, for some tire treads, the tread lugs are in a form of individual lugs and/or of circumferential ribs. For the purpose of this invention, tread lugs and ribs are referred to herein as tread lugs, with intervening grooves, unless otherwise indicated.
When such lug and grooved configured tire treads are driven through water, mud or snow, it is important that the water, mud and snow contained within the tread grooves do not effectively stick to the groove surfaces.
It is therefore an important feature of this invention to provide the surface of the tread grooves with a rubber layer to promote such effect such as, for example, a suitable wet coefficient of friction.
A rubber composition for a tire component has been disclosed which contained a diene based elastomer with carbon black and silica reinforcement together with plasticizer as a combination of polyester phthalate plasticizer, namely Plasthall P900™ from Hallstar Company and dibutoxy ethyl adipate plasticizer as Plasthall DBEA from Hallstar Company individually and in combination. Tire components such as, for example, treads, sidewall, apex, chafer, sidewall insert, wire coat and inner liner are suggested. For example, see U.S. Patent Publication No. 2009/0044892, now abandoned.
In the description of this invention, the terms “rubber” and “elastomer” if used herein, may be used interchangeably, unless otherwise prescribed. The terms “rubber composition”, “compounded rubber” and “rubber compound”, if used herein, are used interchangeably to refer to “rubber which has been blended or mixed with various ingredients and materials” and such terms are well known to those having skill in the rubber mixing or rubber compounding art.
In the description of this invention, the term “phr” refers to parts of a respective material per 100 parts by weight of rubber, or elastomer. The terms “rubber” and “elastomer” may be used interchangeably unless otherwise indicated. The terms “cure” and “vulcanize” may be used interchangeably unless otherwise indicated.